1. Field of the Invention
The present invention relates to a detector arrangement and a detection method. More particularly, the present invention relates to a detector arrangement and a detection method for detecting position information contained in a beam of charged particles, such as in the field of electron microscopy.
2. Background Information
In a conventional scanning electron microscope (SEM), as known, for example, from U.S. Pat. No. 5,578,821, a beam of electrons is focused onto a point (pixel) of the object to be examined. Backscattering electrons, secondary electrons or transmission electrons produced in the object by the electrons of the focused beam are detected by a detector arrangement provided for the respective purpose. A deflector is used to displace the position at which the focused beam impinges on the object. The respective detector arrangements as such are not position-sensitive but integrally receive all backscattering, secondary or transmissions electrons. An image comprising position information of the examined object, however, can be obtained from an intensity of backscattering, secondary or transmission electrons detected by a detector arrangement associated with the position determined by the deflector at which the focused beam impinges on the object. The deflector serves to successively scan the beam over different positions (pixels) of the object, and the intensities allocated to the different positions are detected to compose therefrom the image of the object containing position information. Such a detection method, wherein the intensity of charged particles originating from merely one pixel of the object is constantly detected, is very time-consuming.
U.S. Pat. No. 6,087,659 discloses an electron-microscopic detector arrangement wherein a two-dimensionally extended field on the object is irradiated with primary electrons and wherein secondary electrons emerging from the object are imaged on a position-sensitive detector by means of an optical imaging system. In contrast to the system disclosed in U.S. Pat. No. 5,578,821, this renders it superfluous to sequentially scan merely individual pixels by means of a deflector. Rather, a multiplicity of pixels of the object can be simultaneously detected by means of the position-sensitive detector. An image of the object containing position information can thus be supplied by the position-sensitive detector at once so that it is not necessary to construct this image by composing individual pixels sequentially over time.